Arrangement in rotation pump or motor



H. HAGENES May 2, 1967 2 Sheets-Sheet 1 Filed Oct El, 1965 HARALD HAGENES C 2 y 2, 1967 H. HAGENES 3,316,851

ARRANGEMENT IN ROTATION PUMP OR MOTOR Filed Oct. 21, 1965 2 Sheets-Sheet 2 INVENTO R HARALD HAGENES ATTORNEYS United States Patent 3,316,851 ARRANGEMENT IN ROTATION PUMP OR MOTOR Harald Hagenes, Hust'i Verft & Mek. Verksted, Tonsberg, Norway Filed Oct. 21, 1965, Ser. No. 499,854 3 Claims. (Cl. 103-126) The present invention relates to rotating hydraulic machines, like pumps, motors, etc., of the known type comprising two mutually cooperating gears or rotor elements arranged inside each other and adapted to rotate around mutually parallel axes in such a way that they have substantially the same peripheral speed at their pitch circles, the larger rotor element being rotatably journalled in an adapted bearing house or the like, and the smaller rotor element being rotatably journalled in a casing or cover where an arch-formed groove for the larger rotor element teeth is arranged, these being formed as axially protruding teeth, and suitable supply and delivery conduits for the pumping or working fluid.

Such pumps are previously known from a series of different embodiments. In these previously known constructions the rotor elements have been dimensioned so that their top circles touch each other at a point situated on the central line in the range where the teeth mesh and form a tightening between supply and delivery. In the previously known constructions of this type the tightening between the supply and delivery conduits is based on tooth flanks of two rotor elements engaging each other in the range where they are meshing. Therefore the tightening will depend on the exactness and finish of the tooth flanks, and the efliciency of a pump or motor will be considerably reduced as the tooth flank-s are worn, leakage thereby increasing. As the load for this type of pump and motor often alternates between the two rotor elements, this will result in great wear and tear of the tooth flanks. Even greater wear will result with higher working pressures.

In such known constructions unfavorable conditions are obtained in the intertooth space of the smaller rotor elements where the greater rotor element teeth are situated, as the cavity in this intertooth space will vary during meshing, thus creating cavitation 'and compression of the fluid trapped between the teeth. This causes noise, great undesirable mechanical strain and efliciency loss. These are some of the difficulties which in practice restrict the rotational speed for the previously known pumps and motors of this type.

Such pumps and motors are susbt'antially based on being charged and discharged radially through the gaps formed between the rotor element teeth, and as these gaps are relatively narrow, this will result in throttling or resistance against the charging and discharging with resulting cavitation, pressure impacts, noise and reduced efliciency when the pump or motor is at toov high a rotational speed. In other words, the rotational speed on such a pump or motor of known design is substantially restricted by charging and discharging conditions.

The above-mentioned drawbacks have been eliminated by arranging tooth crowns of the tightening gear, at the place of engagement between the gears projecting radially, somewhat longer out than the rotor teeth and thus creating a tightening between the supply and delivery, only by the tightening gears cooperation with the tightening part of the casing. This solves some of the abovementioned problems. However, unfavorable flow conditions are still experienced for the working fluid which enters, passes and leaves the pump or motor.

To improve these last-mentioned conditions it is proposed, according to the invention, that a rotary pump or motor of the above-mentioned type be so arranged that the tooth crowns of the tightening gear have greater axial length than the rotor teeth, and that the casing conduits are so designed that said charging and discharging generally can take place in axial direction.

For simplicity, the expressions tightening gear and rotor are herein used for the cooperating tooth elements mentioned.

According to the invention the new and characterizing features are achieved by a rotor tooth being meshed between two tightening gear teeth, and leaving free passage between all ranges of the rotor tooth. The relative radial movement between the rotor tooth and the tightening gear, while the tooth passes the tightening range, will result in a corresponding radial displacement of fluid in the tooth space. But due to said free passage past the end of the rotor tooth, no unfavorable local increase of pressure or similar drawbacks, involving noise, wear and tear, and reduced efficiency will arise.

The foregoing and other objects of this invention will be more apparent from the following detailed description, drawings and appended claims.

FIG. 1 is a cross-section of a pump or motor constructed and arranged according to. the invention, the section being taken on the line II of FIG. 2, and

FIG. 2 is an axial section taken on the line IIII of FIG. 1.

The shown pump or motor comprises a large gear or rotor 1, the teeth 2 of which move in a provided arch- -formed groove 4 in the cover 5 which, together with the bearing house 3, form the casing. Eccentrically within the rotor the tightening gear 6 is freely rotatably journalled as clearly seen from FIG. 1. The mesh between the rotor teeth 2 and the tightening gear 6 takes place at the tightening place 5 between the charge and discharge sides of the device. Diametrically opposite this place is, in a way known per se, arranged a crescentshaped part 5" of the cover 5 for sliding fit between the interior crowns of the rotor teeth 2 and the exterior tooth crowns of the tightening gear 6. In said cover 5 there are ports or conduits for the charging and discharging of medium. The rotor 1 is arranged at the end of a shaft 10 The parts so far described are known per se and should need no further detail description.

According to the invention the gears are so dimensioned that the rotor teeth 2 do not protrude as far radially as do the teeth for the tightening gear 6 at the place of engagement between these two gears. As clearly appears from the drawings a cavity 11 is formed between the tightening place 5 of the cover and the positioned tooth of the rotor in the tooth space between the tightening gear teeth 6' and 6". The rotor teeth 2 thus will not abut the tightening part 5 of the casing. Oil or other fluid used for the pump or motor thus cannot be compressed, the volume of the tooth space at the tightening place being constant.

During the relative movement of the teeth past the tightening place 5' further free flow is insured as the rotor teeth 2, according to the invention, have smaller axial extension than the tightening gear teeth. As seen from FIG. 2, a cavity 12 insuring free connection between all parts of the tooth space between the teeth 6' and 6 exists. Thus no fluid can be trapped in any cavity to be compressed and thus cause the drawbacks as stated above.

Further favorable eifect is obtained by the house or the cover for the pump or motor being provided with charging and discharging conduits or ports making it possible for charging and discharging to take place substantially in axial direction. Thus the work spaces between the gears are more easily charged or discharged, and the pump can be run with a considerably higher rotational speed than previously, without creating cavitation or unfavorable pressure impacts.

As will be understood from the above, the described design of the teeth on the rotor and tightening gear will result in the tightening between the charge and discharge sides at the place of engagement in no longer being based on the contact between the tooth flanks, but rather on the slit of the sliding fit between the tooth crowns of the tightening gears and the bore of the house or cover. Thus a slit which is more easy to tighten, is obtained, and the tooth flanks can be produced with less accuracy, and the device can be produced more cheaply than was previously possible. The described device also results in a power moment acting the whole time directly on the rotor teeth, contrary to pumps of similar construction of previously known structures, where the load will alternate between the two gears, necessarily causing vibrations and strains, 'as well as wear and tear of the tooth flanks of the rotor elements. According to the invention the tightening gear will only freely be entrained during rotation, no matter what pressure is used. This results in minimal wear and tear.

According to the invention a pump will give a fluid flow without pulsation, on the condition that the rotor has constant rotational speed.

The amount of fluid per unit of time flowing through a hydraulic pump or motor can, according to the invention, be calculated as the number of rotations multiplied by the volume of the toroidal solid of revolution described by a rotor tooth 2 per rotation. I

Basing the conduits or ports of the casing susbtantially on axial supply and delivery, favorable flow conditions and small hydraulic losses are obtained. In connection with the flow free of pulsation this device gives the possibility of considerably higher rotational speed than previously advisable. The principle of tightening makes a pump or motor of this type suitable for use with considerably higher pressure compared to previous structures of gear pumps having the same dimensioning, and as the tooth flanks move without any noticeable mechanical load even at higher pressures, the durability of the device increases considerably.

According to a modified embodiment the cooperating teeth for rotor and tightening gear are formed to engage each other only with the inner parts. These exterior parts of the teeth are given such a form that a free passage for pumping or working fluid is obtained between said parts. This free passage may exist within the backlash between said parts. This embodiment can give the teeth for rotor and tightening gear approximately the same axial length. There is, however, nothing to prevent the device with different lengths of teeth from being combined with teeth where passages between the exterior parts are formed. In such an embodiment a favorable flow of pumping or working fluid is obtained under certain conditions.

I claim:

1. In apparatus for use as a pump, motor or the like wherein a casing having an inlet port and an outlet port for conducting fluid into and out of said casing has formed therein a chamber bounded by walls having a lower por- 4 tion and an upper portion, said casing including a boss extending into said chamber and forming a groove bounded by a lower portion of said boss and said lower wall portion, said groove being of uniform width subtantially concentric with said casing, and wherein a first gear is disposed within said chamber having teeth adapted for movement through said groove in sliding relationship with said lower portion of said boss and said lower portion of said chamber, wherein a second idling gear matingly cooperating with said first gear is disposed eccentrically within an upper portion of said chamber and within said first gear such that the teeth of said first and second gears mesh, the improvement which comprises: a

a boss extending from said upper portion of the chamber into the chamber, said boss having a surface portion substantially parallel to the locus of points on said gears during movement thereof, the crowns of said second gear protruding radially farther than the crowns of said first gear such that a reduction in fluid volume occurs between said inlet and said outlet ports only by cooperation of said second gear with said surface portion, said inlet and outlet adapted to conduct fluid in a substantially axial direction.

2. In apparatus for use as a pump, motor or the like having a casing with inlet and outlet ports formed therein, and wherein a driving crown gear and an idler spur gear intermesh and are disposed within said casing, said idler gear mounted eccentrically with respect to said corwn gear and-meshing internally therewith, said casing including an associated cover having a boss extending within said casing for closing an interspace between said crown gear and said idler gear, said idler gear having teeth which protrude radially in a greater amount than the teeth of said crown gear at the place of meshing engagement therebetween for producing tightening only by cooperation of said idler gear with an upper portion of the casing, the improvement comprising:

the teeth of said idler gear extending in an axial direction with respect to said casing a greater predetermined amount than the teeth of said crown gear, said casing formed such that said inlet and outlet ports charge and discharge fluid in a substantially axial direction.

3. In apparatus according to claim 2, wherein only inner portions of said crown gear teeth engage inner portions of said idler gear teeth.

References Cited by the Examiner UNITED STATES PATENTS Roenick 103-126 DONLEY J. STOCKING, Primary Examiner.

WILBUR J. GOODLIN, Examiner. 

1. IN APPARATUS FOR USE AS A PUMP, MOTOR OR THE LIKE WHEREIN A CASING HAVING AN INLET PORT AND AN OUTLET PORT FOR CONDUCTING FLUID INTO AND OUT OF SAID CASING HAS FORMED THEREIN A CHAMBER BOUNDED BY WALLS HAVING A LOWER PORTION AND AN UPPER PORTION, SAID CASING INCLUDING A BOSS EXTENDING INTO SAID CHAMBER AND FORMING A GROOVE BOUNDED BY A LOWER PORTION OF SAID BOSS AND SAID LOWER WALL PORTION, SAID GROOVE BEING OF UNIFORM WIDTH SUBTANTIALLY CONCENTRIC WITH SAID CASING, AND WHEREIN A FIRST GEAR IS DISPOSED WITHIN SAID CHAMBER HAVING TEETH ADAPTED FOR MOVEMENT THROUGH SAID GROOVE IN SLIDING RELATIONSHIP WITH SAID LOWER PORTION OF SAID BOSS AND SAID LOWER PORTION OF SAID CHAMBER, WHEREIN A SECOND IDLING GEAR MATINGLY COOPERATING WITH SAID FIRST GEAR IS DISPOSED ECCENTRICALLY WITHIN AN UPPER PORTION OF SAID CHAMBER AND WITHIN SAID FIRST GEAR SUCH THAT THE TEETH OF SAID FIRST AND SECOND GEARS MESH, THE IMPROVEMENT WHICH COMPRISES: A BOSS EXTENDING FROM SAID UPPER PORTION OF THE CHAMBER INTO THE CHAMBER, SAID BOSS HAVING A SURFACE PORTION SUBSTANTIALLY PARALLEL TO THE LOCUS OF POINTS ON SAID GEARS DURING MOVEMENT THEREOF, THE CROWNS OF SAID SECOND GEAR PROTRUDING RADIALLY FARTHER THAN THE CROWNS OF SAID FIRST GEAR SUCH THAT A REDUCTION IN FLUID VOLUME OCCURS BETWEEN SAID INLET AND SAID OUTLET PORTS ONLY BY COOPERATION OF SAID SECOND GEAR WITH SAID SURFACE PORTION, SAID INLET AND OUTLET ADAPTED TO CONDUCT FLUID IN A SUBSTANTIALLY AXIAL DIRECTION. 